A ceramic matrix composite (CMC) is a material including reinforcing ceramic fibers embedded in a ceramic matrix. CMCs can exhibit a variety of desirable properties, such as high temperature stability, high thermal resistance, high mechanical integrity, high hardness, high corrosion resistance, light weight, nonmagnetic properties, and nonconductive properties. CMCs can thus be used to form a number of industrial and military structures including, for example, aerospace, marine, and automotive structures requiring one or more of the aforementioned properties.
One approach toward forming CMC structures includes the use of resin transfer molding (RTM). To form a CMC structure using RTM, ceramic fibers are placed into a mold in a desired arrangement. The mold is then evacuated, a resin is introduced into the mold under pressure, and the temperature of the mold is controlled to enable the resin to set. The resin is then cured and pyrolyzed at elevated temperatures to form the CMC structure. Unfortunately, however, RTM is generally limited to use in forming relatively small CMC structures (e.g., due to mold size limitations), and can result in ceramic matrix uniformity issues. For example, gas bubbles can be introduced into or evolve within the resin during processing that cannot escape or are difficult to remove during cure and pyrolysis. Consequently, the gas bubbles may be present in the ceramic matrix of the CMC structure, and can negatively affect the desired properties thereof.
Another approach toward forming CMC structures includes the use of chemical vapor infiltration (CVI). To form a CMC structure using CVI, dry ceramic fiber preforms, such as dry ceramic woven fabrics, are placed on a tool in a desired arrangement to form a dry ceramic fiber structure. A chemical vapor deposition (CVD) process is then used to infiltrate the dry ceramic fiber structure with a ceramic matrix and form the CMC structure. Unfortunately, however, CVI requires complex and costly tooling to ensure that the dry ceramic fiber structure is appropriately shaped, and to ensure the CMC structure includes a uniform ceramic matrix. In addition, the nature of the CVD process typically limits the reusability of the tooling, significantly adding to CMC structure fabrication costs.
Yet another approach toward forming CMC structures involves hand placement (e.g., lay up) of ceramic fiber preforms, such as ceramic tapes or ceramic woven fabrics, infiltrated with a pre-ceramic matrix slurry onto a tool to form an uncured composite material structure. The uncured composite material structure is then cured and either sintered or pyrolyzed to form a desired CMC structure. Unfortunately, however, such processing can be prohibitively expensive as hand placement can be time and labor intensive, as well as enhancing potential for product defects due to human error.
Yet still another approach toward forming CMC structures involves filament winding of ceramic fiber tows infiltrated with a pre-ceramic matrix slurry onto a tool to form an uncured composite material structure. The uncured composite material structure is then cured and either sintered or pyrolyzed to form a desired CMC structure. Unfortunately, however, filament winding is generally limited to forming CMC structures that are substantially cylindrical in shape. Namely, the tool upon which the tows are wound is generally limited to being substantially cylindrical in shape so that the tows follow a placement path permitting the tows to remain in place on the tool (i.e., a geodesic path).
It would, therefore, be desirable to have new methods, systems, and apparatuses for forming a CMC structure that are easy to employ, cost-effective, fast, and more versatile as compared to conventional methods, systems, and apparatuses for forming CMC structures. Such methods, systems, and apparatuses may, for example, facilitate increased adoption and use of CMC structures in industrial and military applications.